University of North Carolina-Chapel Hill

Project Summary (1995-2000)

The overall goal of this project is to assess how microorganisms mediate the fate of polynuclear aromatic hydrocarbons (PAH) in soil environments. Microbial metabolism of PAHs have been shown by many investigators to create by-products that can be more or less toxic than the starting material and are certainly more environmentally mobile. Among the fates of both the parent PAHs and their stable degradation products are further microbial metabolism, often to products like CO₂. An alternative fate, the potential for which has only recently been recognized, is interaction with the organic fraction of soil (SOM) that may lead to the immobilization of the compounds or by-products into the SOM. Immobilization could represent a new strategy for bioremediation that may be simpler and more cost effective to manage than other technologies. Experiments investigate which characteristics of the soil and the microbial community can be manipulated to impact biodegradation versus immobilization. These include fractionation of the soil carbon to determine which most strongly binds PAH, how this impacts the toxicity, how manipulation of the soil microbial community can impact the binding and fate, and whether this can be influenced in soil environments as a remediation strategy.